Trench power MOSFET (or trench MOS) devices have a broad application within the semiconductor industry. More specifically, high aspect narrow-width deep-trench MOS devices are preferred due to the fact that these trenches provide better isolation between transistors, hence, improving significantly various electrical and physical properties of the device.
For high aspect narrow-width deep-trench MOS, a thick bottom oxide is required for the purpose of isolation in order to reduce the gate-drain charge, especially during high-speed switching. Due to its dimensions, conventional fabrication methods that employ the technique of grown oxide will not be able to provide efficient filling to obtain a thick bottom oxide in the narrow-width deep-trench.